Some birds migrate more than 70,000 kilometers in order to avoid winter and find food. Scientists believe that birds migrate in a variety of ways, such as those similar to humans, based on topographical features (such as coastlines and mountains) to determine location.
A further approach is to determine the direction by the position of the sun and the stars, which many birds will do.
Some birds can determine the route by sensing the Earth’s magnetic field, because some part of the brain has a compass-like function.
Most birds will decide when to migrate according to the length of day and night and the temperature, because these changes will affect their hormones, let them know when to migrate.